1. Field of Invention
This invention relates generally to wood preservative compositions containing metal compounds that are environmentally safe and methods of treating wood and other cellulose fibers using those compositions.
2. Description of Related Art
The following prior art references are incorporated in their entirety herein. Wood preservative compositions of aqueous solutions containing metal compounds have been used for many applications. The wood preservation solution is applied by various methods including, injection in pressure vessels, immersion in open vessels, and by brushing or spray painting onto the wood surface or other cellulose fiber.
Compounds used as the active ingredient in wood preservation solutions include copper compounds, such as, but not limited to copper acetate; chrome compounds, such as, but not limited to potassium chromate; and arsenic compounds, such as but not limited to, arsenious acid. (for example see U.S. Pat. No. 5,207,583). CCA (Copper, chromium, arsenic) wood preservatives have produced good protection against wood decay, but are not environmentally safe.
The copper and arsenic provide fungicidal activity and the chromium acts to fix the copper to the wood. Aluminum compounds, such as aluminum halohydrates provide improved water repellency of cellulose when used as a component of CCA formulations (U.S. Pat. No. 4,212,249).
Zirconium complexes have also been shown to provide water repellency and enhance the antimicrobial action of copper. According to U.S. Pat. No. 4,737,491, the zirconium complex may be added as a separate salt or incorporated into a metal amine polymer and complex. The penetration of these complexes is limited by polymer molecular weight and configuration. Hydrophobic components in the formulation will decrease the effectiveness of the solution.
Zirconium has also been described as an inert fixing agent for borates in wood preservation compositions (U.S. Pat. No. 5,612,094). This approach has proven ineffective. In some cases a fixing agent such as acetic acid is added to the wood preservative formulation. When these formulations are applied to wood a series of reactions take place between the components of the preservative solution (ie fixing agent, metal) and the wood fibers. These reactions fix the preservative to the wood resulting in improved resistance to leaching. Unfortunately this method also reduces penetration and diminishes the activity of the preservative.
U.S. Pat. No. 3,725,544 (Raff et al.) discloses that aluminum based wood preservatives may have other metals.
U.S. Pat. No. 3,889,020 (Amundsen et al.) discloses treating wooden objects with a blend of pentachlorophenol and a petroleum hydrocarbon in claimed amounts. The compositions as disclosed in column 3, may also contain zirconium and copper, but not aluminum.
U.S. Pat. No. 4,212,249 discloses aluminum compounds, such as aluminum halohydrates that apparently provide improved water repellency of cellulose when used as a component of CCA formulations. Zirconium complexes have also been shown to provide water repellency and enhance the antimicrobial action of copper.
U.S. Pat. No. 4,218,249 (Hill) discloses copper and aluminum mixed with chromium hexavalent and even copper-arsenic mixtures.
U.S. Pat. No. 4,303,726 (Turner) discloses an aluminum based wood preservative that may have additional divalent metals such as zinc and at least one carboxylic acid radical.
U.S. Pat. No. 4,737,491 (Leppavuori) discloses that a zirconium complex may be added as a separate salt or incorporated into a metal amine polymer and complex. The penetration of these complexes is limited by polymer molecular weight and configuration. Hydrophobic components in the formulation will decrease the effectiveness of the solution.
U.S. Pat. No. 4,783,221 (Grove) discloses an organic compound based wood preservative composition comprising at least one metal salt of an organic carboxylic acid containing at least about 6 carbon atoms, wherein the metal may be zinc, mercury, antimony and lead, and at least one isothiazolone compound.
U.S. Pat. No. 5,207,583 discloses wood preservative compositions of aqueous solutions containing metal compounds. The wood preservation solution is applied by various methods including, injection in pressure vessels, immersion in open vessels, and by brushing or spray painting on a wood surface. Compounds used as the active ingredient in wood preservation solutions include; copper compounds, such as copper acetate; chrome compounds, such as potassium chromate; and arsenic compounds, such as arsenious acid. (for example see CCA (Copper, chromium, arsenic) wood preservatives have produced good protection against wood decay, but are not environmentally safe. The copper and arsenic provide fungicidal activity and the chromium acts to fix the copper to the wood.
U.S. Pat. No. 5,612,094 (Schubert et al.) discloses that zirconium has also been described as an inert fixing agent for borates in wood preservation compositions. In some cases a fixing agent such as acetic acid is added to the wood preservative formulation. When these formulations are applied to wood, a series of reactions take place between the components of the preservative solution (i.e., fixing agent, metal) and the wood fibers. These reactions fix the preservative to the wood resulting in improved resistance to leaching. Unfortunately, this method also reduces penetration and diminishes the activity of the preservative.
U.S. Pat. No. 5,733,666 (Sinko) discloses a composition to reduce the staining of coatings comprising a zirconyl compound in a liquid, and a lanthanide compound to provide UV protection. Additional metals such as chromium and copper and aluminum are disclosed.
U.S. Pat. No. 6,441,016 (Gottschalk et al.) discloses a wood preservative of copper and an alkanolamine and cyproconazole and an emulsifier.
U.S. Pat. No. 6,503,936 (Schelberger et al.) discloses a wood preservative of metals such as aluminum and copper, but zirconium is not detailed. The claims discuss a fungicidal composition of the formula I carbamate and a copper-containing fungicidal active compound, where they are present in synergistically effective amounts.
U.S. Pat. No. 6,541,038 (Tanaka et al.) discloses a metal ion based wood preservative containing zirconium, copper and aluminum, but also as fire retardants. The formulations also contain lignin and/or lignin derivatives to fix the metal in the wood.
U.S. Pat. No. 6,579,354 (West) discloses copper and aluminum based wood preservatives without zinc base and without environmentally challenged hexavalent chromium. The composition includes a water soluble acidic copper pesticide combined with aluminum nitrate wherein the weight ratio of aluminum nitrate to copper is from a:10 to 10:1.
U.S. Pat. No. 6,623,552 (West) discloses aluminum based wood protectives, but without copper or zirconium to protect the wood from UV degradation and agents.
U.S. Published Application No. 2002/0007926 (Jewell et al.) discloses copper based biocidals for cellulose fibers, but does not disclose aluminum or zirconium.
U.S. Published Application No. 2002/0071806 (Sabacky et al.) discloses methods of making metal salt mixtures but not directed to wood preservatives.
U.S. Published Application No. 2003/0041983 (Jewell et al.) discloses copper based biocidal for cellulose fibers such as wood pulp, but does not disclose aluminum or zirconium.
U.S. Published Application No. 2004/0055719 (Jewell et al.) discloses copper based biocidal for cellulose fibers such as wood pulp, but does not disclose aluminum or zirconium.
U.S. Published Application No. 2004/0258768 (Hodge et al.) discloses copper based wood preservatives that may have other metal ions but zirconium and aluminum are not disclosed.